FvwmM4(1) on Linux
The text d629694b6ced, as Debian 8 (Jessie) shipped it.
the fvwm M4 pre-processor
Flags it lists
-
-debug -
-lock -
-m4-equote -
-m4-prefix -
-m4-prefix-defines -
-m4-squote -
-m4opt -
-m4prog -
-noread -
-outfile